Lettuce line rx17275496

ABSTRACT

The invention provides seed and plants of the lettuce line designated RX17275496. The invention thus relates to the plants, seeds and tissue cultures of lettuce line RX17275496, and to methods for producing a lettuce plant produced by crossing a plant of lettuce line RX17275496 with itself or with another lettuce plant, such as a plant of another line. The invention further relates to seeds and plants produced by such crossing. The invention further relates to parts of a plant of lettuce line RX17275496, including the gametes of such plants.

FIELD OF THE INVENTION

The present invention relates to the field of plant breeding and, morespecifically, to the development of lettuce line RX17275496.

BACKGROUND OF THE INVENTION

The goal of vegetable breeding is to combine various desirable traits ina single variety/hybrid. Such desirable traits may include greateryield, resistance to insects or pests, tolerance to heat and drought,better agronomic quality, higher nutritional value, growth rate andfruit properties.

Breeding techniques take advantage of a plant's method of pollination.There are two general methods of pollination: a plant self-pollinates ifpollen from one flower is transferred to the same or another flower ofthe same plant or plant variety. A plant cross-pollinates if pollencomes to it from a flower of a different plant variety.

Plants that have been self-pollinated and selected for type over manygenerations become homozygous at almost all gene loci and produce auniform population of true breeding progeny, a homozygous plant. A crossbetween two such homozygous plants of different varieties produces auniform population of hybrid plants that are heterozygous for many geneloci. Conversely, a cross of two plants each heterozygous at a number ofloci produces a population of hybrid plants that differ genetically andare not uniform. The resulting non-uniformity makes performanceunpredictable.

The development of uniform varieties requires the development ofhomozygous inbred plants, the initial crossing of these inbred plants,and the evaluation of the crosses and their progenies obtained byselfing. Pedigree breeding and recurrent selection are examples ofbreeding methods that have been used to develop inbred plants frombreeding populations. Those breeding methods combine the geneticbackgrounds from two or more plants or various other broad-based sourcesinto breeding pools from which new lines are developed by selfing andselection of desired phenotypes. The new lines are evaluated todetermine which of those have commercial potential.

One crop species which has been subject to such breeding programs and isof particular value is lettuce. Lettuce, Lactuca sativa, is a temperateannual or biennial plant most often grown as a leaf vegetable. Lettucebelongs to the family Asteraceae (or Compositae). Other members of thisfamily include endive, chicory, artichoke, sunflower and safflower. Itis closely related to common wild lettuce or prickly lettuce (L.serriola) and less closely related to two other wild lettuces (L.saligna and L. virosa). Lettuce and sunflower are the best geneticallycharacterized members of this family. Four principal types of lettuceinclude crisphead (mostly iceberg), romaine (cos), leaf and butterhead.Each of these basic groups is comprised of numerous cultivars, eachcharacterized by its own particular morphology, disease resistance andcultural adaptations. These types vary in size, shape, texture, color,nutritional value and taste. The principal nutrients are vitamins A andC and calcium, and the percentage water content in lettuce is high(e.g., 93-96%).

A lettuce plant has a short stem initially, but when it blooms, the stemlengthens and branches, producing many flower heads that look like thoseof dandelions, but smaller. This is called bolting. When grown to eat,lettuce is harvested before it bolts. In the United States, more than90% of the nation's lettuce is grown in California and Arizona. InCalifornia, variations in temperature in the regions where lettuce isgrown allows for a continuous supply of lettuce year-round, although thegreatest supply is from May through October.

Lettuce is a diploid species with 2N=18 chromosomes and naturallyself-pollinates. The self-pollination feature leads to inbred lines thatare uniform and vigorous, and therefore exhibit extensive genetichomozygosity. Virtually all commercial cultivars in use today are inbredlines. Hybrid development has not been pursued with much interest due tothe tedious nature of manual crossing and low seed production per cross.Furthermore, there is no consistent large-scale pollen movement byinsects or wind.

The principal breeding mechanisms are pedigree breeding andbackcrossing, but straight selection of desirable plants within acultivar is also practiced to slightly modify the cultivar. Choice ofbreeding or selection methods depends on, for example, the mode of plantreproduction, the heritability of the trait(s) being improved and thetype of cultivar used commercially. Since the flowers of lettuce aredelicate and emasculation is tedious and difficult, lettuce breederstypically wait until the flowers open and then wash away the self-pollenprior to crossing.

While breeding efforts to date have provided a number of useful lettucelines with beneficial traits, there remains a great need in the art fornew lines with further improved traits. Such plants would benefitfarmers and consumers alike by improving crop yields and/or quality.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a lettuce plant of theline designated RX17275496. Also provided are lettuce plants having allthe physiological and morphological characteristics of the lettuce linedesignated RX17275496. Parts of the lettuce plant of the presentinvention are also provided, for example, including pollen, an ovule anda cell of the plant.

The invention also concerns seed of lettuce line RX17275496. The lettuceseed of the invention may be provided as an essentially homogeneouspopulation of lettuce seed of the line designated RX17275496.Essentially homogeneous populations of seed are generally free fromsubstantial numbers of other seed. Therefore, seed of line RX17275496may be defined as forming at least about 97% of the total seed,including at least about 98%, 99%, or more of the seed. The populationof lettuce seed may be particularly defined as being essentially freefrom hybrid seed. The seed population may be separately grown to providean essentially homogeneous population of lettuce plants designatedRX17275496.

In another aspect of the invention, a plant of lettuce line RX17275496comprising an added heritable trait is provided. The heritable trait maycomprise a genetic locus that is a dominant or recessive allele. In oneembodiment of the invention, a plant of lettuce line RX17275496 isdefined as comprising a single locus conversion. In specific embodimentsof the invention, an added genetic locus confers one or more traits suchas, for example, herbicide tolerance, insect resistance, diseaseresistance, and modified carbohydrate metabolism. The trait may be, forexample, conferred by a naturally occurring gene introduced into thegenome of the line by backcrossing, a natural or induced mutation, or atransgene introduced through genetic transformation techniques into theplant or a progenitor of any previous generation thereof. Whenintroduced through transformation, a genetic locus may comprise one ormore transgenes integrated at a single chromosomal location.

In another aspect of the invention, a tissue culture of regenerablecells of a plant of line RX17275496 is provided. The tissue culture willpreferably be capable of regenerating plants capable of expressing allof the physiological and morphological characteristics of the line, andof regenerating plants having substantially the same genotype as otherplants of the line. Examples of some of the physiological andmorphological characteristics of the line RX17275496 include thosetraits set forth in the tables herein. The regenerable cells in suchtissue cultures may be derived, for example, from embryos, meristems,cotyledons, pollen, leaves, anthers, roots, root tips, pistil, flower,seed and stalks. Still further, the present invention provides lettuceplants regenerated from a tissue culture of the invention, the plantshaving all the physiological and morphological characteristics of lineRX17275496.

In yet another aspect of the invention, processes are provided forproducing lettuce seeds and plants, which processes generally comprisecrossing a first parent lettuce plant with a second parent lettuceplant, wherein at least one of the first or second parent lettuce plantsis a plant of the line designated RX17275496. These processes may befurther exemplified as processes for preparing hybrid lettuce seed orplants, wherein a first lettuce plant is crossed with a second lettuceplant of a different, distinct line to provide a hybrid that has, as oneof its parents, the lettuce plant line RX17275496. In these processes,crossing will result in the production of seed. The seed productionoccurs regardless of whether the seed is collected or not.

In one embodiment of the invention, the first step in “crossing”comprises planting seeds of a first and second parent lettuce plant,often in proximity so that pollination will occur for example, mediatedby insect vectors. Alternatively, pollen can be transferred manually.Where the plant is self-pollinated, pollination may occur without theneed for direct human intervention other than plant cultivation.

A second step may comprise cultivating or growing the seeds of first andsecond parent lettuce plants into plants that bear flowers. A third stepmay comprise preventing self-pollination of the plants, such as byemasculating the male portions of flowers, (i.e., treating ormanipulating the flowers to produce an emasculated parent lettuceplant). Self-incompatibility systems may also be used in some hybridcrops for the same purpose. Self-incompatible plants still shed viablepollen and can pollinate plants of other varieties but are incapable ofpollinating themselves or other plants of the same line.

A fourth step for a hybrid cross may comprise cross-pollination betweenthe first and second parent lettuce plants. Yet another step comprisesharvesting the seeds from at least one of the parent lettuce plants. Theharvested seed can be grown to produce a lettuce plant or hybrid lettuceplant.

The present invention also provides the lettuce seeds and plantsproduced by a process that comprises crossing a first parent lettuceplant with a second parent lettuce plant, wherein at least one of thefirst or second parent lettuce plants is a plant of the line designatedRX17275496. In one embodiment of the invention, lettuce seed and plantsproduced by the process are first generation (F₁) hybrid lettuce seedand plants produced by crossing a plant in accordance with the inventionwith another, distinct plant. The present invention further contemplatesplant parts of such an F₁ hybrid lettuce plant, and methods of usethereof. Therefore, certain exemplary embodiments of the inventionprovide an F₁ hybrid lettuce plant and seed thereof.

In still yet another aspect of the invention, the genetic complement ofthe lettuce plant line designated RX17275496 is provided. The phrase“genetic complement” is used to refer to the aggregate of nucleotidesequences, the expression of which sequences defines the phenotype of,in the present case, a lettuce plant, or a cell or tissue of that plant.A genetic complement thus represents the genetic makeup of a cell,tissue or plant, and a hybrid genetic complement represents the geneticmake up of a hybrid cell, tissue or plant. The invention thus provideslettuce plant cells that have a genetic complement in accordance withthe lettuce plant cells disclosed herein, and plants, seeds and plantscontaining such cells.

Plant genetic complements may be assessed by genetic marker profiles,and by the expression of phenotypic traits that are characteristic ofthe expression of the genetic complement, e.g., isozyme typing profiles.It is understood that line RX17275496 or a first generation progenythereof could be identified by any of the many well known techniquessuch as, for example, Simple Sequence Length Polymorphisms (SSLPs)(Williams et al., 1990), Randomly Amplified Polymorphic DNAs (RAPDs),DNA Amplification Fingerprinting (DAF), Sequence Characterized AmplifiedRegions (SCARs), Arbitrary Primed Polymerase Chain Reaction (AP-PCR),Amplified Fragment Length Polymorphisms (AFLPs) (EP 534 858,specifically incorporated herein by reference in its entirety), andSingle Nucleotide Polymorphisms (SNPs) (Wang et al., 1998).

In still yet another aspect, the present invention provides hybridgenetic complements, as represented by lettuce plant cells, tissues,plants, and seeds, formed by the combination of a haploid geneticcomplement of a lettuce plant of the invention with a haploid geneticcomplement of a second lettuce plant, preferably, another, distinctlettuce plant. In another aspect, the present invention provides alettuce plant regenerated from a tissue culture that comprises a hybridgenetic complement of this invention.

In still yet another aspect, the invention provides a plant of an inbredlettuce line that exhibits a combination of traits comprising: aButterhead lettuce adapted to open-field growth; a mid-dark leaf color;a thick and smooth leaf; a fine and flat bottom; good bolting resistancewhen grown in the field; white seed; resistance to races 1-26 of Bremialectucae (downy mildew), resistance to strain 0 of Nasonovia ribisnigri(Nr:0), and resistance to strain Ls-1 of lettuce mosaic virus (LMV); andease in harvesting and processing. In certain embodiments, thecombination of traits may be defined as controlled by genetic means forthe expression of the combination of traits found in lettuce lineRX17275496.

In still yet another aspect, the invention provides a method ofdetermining the genotype of a plant of lettuce line RX17275496comprising detecting in the genome of the plant at least a firstpolymorphism. The method may, in certain embodiments, comprise detectinga plurality of polymorphisms in the genome of the plant. The method mayfurther comprise storing the results of the step of detecting theplurality of polymorphisms on a computer readable medium. The inventionfurther provides a computer readable medium produced by such a method.

In still yet another aspect, the present invention provides a method ofproducing a plant derived from line RX17275496, the method comprisingthe steps of: (a) preparing a progeny plant derived from lineRX17275496, wherein said preparing comprises crossing a plant of theline RX17275496 with a second plant; and (b) crossing the progeny plantwith itself or a second plant to produce a seed of a progeny plant of asubsequent generation. In further embodiments, the method mayadditionally comprise: (c) growing a progeny plant of a subsequentgeneration from said seed of a progeny plant of a subsequent generationand crossing the progeny plant of a subsequent generation with itself ora second plant; and repeating the steps for an additional 3-10generations to produce a plant derived from line RX17275496. The plantderived from line RX17275496 may be an inbred line, and theaforementioned repeated crossing steps may be defined as comprisingsufficient inbreeding to produce the inbred line. In the method, it maybe desirable to select particular plants resulting from step (c) forcontinued crossing according to steps (b) and (c). By selecting plantshaving one or more desirable traits, a plant derived from lineRX17275496 is obtained which possesses some of the desirable traits ofthe line as well as potentially other selected traits.

In certain embodiments, the present invention provides a method ofproducing lettuce comprising: (a) obtaining a plant of lettuce lineRX17275496, wherein the plant has been cultivated to maturity, and (b)collecting lettuce from the plant.

In further embodiments of the invention, a plant or any trait thereofmay be described in terms of a color value(s) on the Royal HorticulturalSociety (RHS) color chart. This chart and the use thereof are well knownin the art. It is further well known to those of skill in the art thatother systems of color assessment are available and may be used todescribe color in connection with any particular plant or trait thereof,including those described herein.

Any embodiment discussed herein with respect to one aspect of theinvention applies to other aspects of the invention as well, unlessspecifically noted.

The term “about” is used to indicate that a value includes the standarddeviation of error for the device or method being employed to determinethe value. The use of the term “or” in the claims is used to mean“and/or” unless explicitly indicated to refer to alternatives only orthe alternatives are mutually exclusive, although the disclosuresupports a definition that refers to only alternatives and to “and/or.”When used in conjunction with the word “comprising” or other openlanguage in the claims, the words “a” and “an” denote “one or more,”unless specifically noted. The terms “comprise,” “have” and “include”are open-ended linking verbs. Any forms or tenses of one or more ofthese verbs, such as “comprises,” “comprising,” “has,” “having,”“includes” and “including,” are also open-ended. For example, any methodthat “comprises,” “has” or “includes” one or more steps is not limitedto possessing only those one or more steps and also covers otherunlisted steps. Similarly, any plant that “comprises,” “has” or“includes” one or more traits is not limited to possessing only thoseone or more traits and covers other unlisted traits.

Other objects, features and advantages of the present invention willbecome apparent from the following detailed description. It should beunderstood, however, that the detailed description and any specificexamples provided, while indicating specific embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides methods and compositions relating to plants,seeds and derivatives of lettuce line RX17275496. This line showsuniformity and stability within the limits of environmental influencefor the traits described hereinafter. Lettuce line RX17275496 providessufficient seed yield. By crossing with a distinct second plant, uniformF1 hybrid progeny can be obtained.

Line RX17275496 exhibits a number of improved traits including: aButterhead lettuce adapted to open-field growth; a mid-dark leaf color;a thick and smooth leaf; a fine and flat bottom; good bolting resistancewhen grown in the field; white seed; resistance to races 1-26 of Bremialectucae (downy mildew), resistance to strain 0 of Nasonovia ribisnigri(Nr:0), and resistance to strain Ls-1 of lettuce mosaic virus (LMV); andease in harvesting and processing. The development of the line can besummarized as follows.

A. Origin and Breeding History of Lettuce Line RX17275496

Line RX17275496 was produced by repeated generations of selfing andsingle plant selections from the parents [OX{(SXD)X(MXC)}] and{NASX(VBXR25)} through pedigree selection as follows:

female male [OX {(SXD)X(MXC)}] x {NASX(VBXR25)} F1 single plantselection and self ↓ F2 single plant selection and self ↓ F3 singleplant selection and self ↓ F4 single plant selection and self ↓ F5single plant selection and self ↓ F6 single plant selection and self ↓F7 (RX17275496) self and bulk ↓ F8 (RX17275496) field trials

After the initial cross, the F1 plant was selfed. The F2 populationobtained therefrom was sowed and a single plant was selected and selfed.Single plant selections were made in subsequent years until the F7 whenthe line was judged uniform for trialing. The F7 plants were selfedwithout any selection and their seeds were bulked and used for trialing.

B. Physiological and Morphological Characteristics of Lettuce LineRX17275496

In accordance with one aspect of the present invention, there isprovided a plant having the physiological and morphologicalcharacteristics of lettuce line RX17275496. A description of thephysiological and morphological characteristics of lettuce lineRX17275496 is presented in Table 1.

TABLE 1 Physiological and Morphological Characteristics of LineRX17275496 and Selected Lines Comparison Line Comparison Line-Dark GreenCHARACTERISTIC RX17275496 Line-Touareg Boston 1. Type ButterheadButterhead Butterhead 2. Seed Color white (US = Silver white white Gray)[TG = Verpia] (US = Silver Gray) (US = Silver Gray) [TG = Verpia] [TG =Verpia] Light dormancy light not required light not required light notrequired Heat dormancy susceptible susceptible susceptible 3. Seedlinganthocyanin coloration absent (Verpia) absent (Verpia) absent (Verpia)size of cotyledon (fully small (Expresse) small (Romance) mediumdeveloped) (Expresse) shape of cotyledon medium elliptic medium ellipticbroad elliptic (Frisette) (Frisette) (Fiorella, Sunrise) 4. Leaf shapeof cotyledons intermediate intermediate broad shape of fourth leaf ovalelongate elongate length/width index of 13.38 13.63 15.9 fourth leaf(length / width × 10) apical margin finely dentate finely dentate finelydentate (cotyledon to 4^(th) leaf stage) basal margin finely dentatemoderately moderately (cotyledon to 4^(th) leaf dentate dentate stage)undulation (cotyledon slight medium slight to 4^(th) leaf stage greencolor (cotyledon medium green light green medium green to 4^(th) leafstage) anthocyanin absent absent absent distribution (cotyledon to4^(th) leaf stage) rolling (cotyledon to 4^(th) absent absent presentleaf stage) cupping (cotyledon to uncupped uncupped uncupped 4^(th) leafstage) reflexing (cotyledon to none apical margin apical and lateral4^(th) leaf stage) and lateral margins margins attitude at 10-12 leafsemi-erect (Great semi-erect (Great semi-erect (Great stage Lakes 118,Soraya) Lakes 118, Lakes 118, Soraya) Soraya) division at 10-12 leafentire (Fiorella, entire (Fiorella, entire (Fiorella, stage sunrise)sunrise) sunrise) incisions of margin on absent (Verpia) absent (Verpia)absent (Verpia) apical part depth of incisions on absent/shallow (US:absent/shallow absent/shallow margin on apical part Dark Green Boston)(US: Dark Green (US: Dark Green (harvest mature outer [TG: Pentared,Boston) [TG: Boston) [TG: leaves) Unicum] Pentared, Pentared, Unicum]Unicum] venation not flabellate not flabellate not flabellate(Donatella, Verpia, (Donatella, (Donatella, Xanadu) Verpia, Xanadu)Verpia, Xanadu) mature leaves: entire (Dark Green entire (Dark entire(Dark indentation finest Boston) Green Boston) Green Boston) divisionsof the margin (harvest mature outer leaves) degree of undulation of weakweak absent/slight/ apical margin (harvest [TG: Commodore, [TG: veryweak (US: mature outer leaves) Sunrise] Commodore, Dark Green Sunrise]Boston) [TG: Dustin, Manfred] green color (harvest medium green lightgreen medium green mature outer leaves) (Great Lakes) (Minetto) (GreatLakes) hue of green color of absent (Donatello, absent absent outerleaves Verpia) (Donatello, (Donatello, Verpia) Verpia) intensity ofcolor of medium light medium outer leaves anthocyanin coloration absent[TG: absent [TG: absent [TG: Fiorella, Sunrise] Fiorella, Sunrise]Fiorella, Sunrise] size medium medium medium glossiness of upper sidemoderate/medium dull/weak (US: absent or very (harvest mature outer (US:Salinas) Vanguard) [TG: weak [TG: leaves) [TG: Feria, Sunrise] Elsa,Fiorella] Divina, Du bon jardinier] blistering (harvest moderate/mediumabsent/slight or weak ([TG: mature outer leaves) (US: Vanguard) veryweak (US: Fiorella, Minas]) [TG: Commodore] Salinas) [TG: Donia,Frillblond] size of blisters medium (Dustin, medium (Dustin, medium(Dustin, Sunrise) Sunrise) Sunrise) thickness (harvest medium (Dustin,medium (Dustin, medium (Dustin, mature outer leaves) Sunrise) Sunrise)Sunrise) trichomes (harvest absent (smooth) absent (smooth) absent(smooth) mature outer leaves) attitude at harvest semi-erect (Amelia,semi-erect semi-erect maturity (outer leaves Toronto (Amelia, Toronto(Amelia, Toronto from head lettuce or adult leaves from cutting and stemlettuce) shape transverse broad broad elliptic transverse broad elliptic(Amadeus, elliptic (Commodore, Amelia) (Commodore, Fiorella) Fiorella)shape of tip rounded (Blonde rounded (Blonde rounded (Blonde Maraîchère,Maraîchère, Maraîchère, Maserati) Maserati) Maserati) 5. Plant spread offrame leaves 32.14 cm 31.15 cm 27.77 cm diameter medium (Clarion, mediumsmall (Bastion, Verpia) Gotte à graine blanche) height (flowering plant)medium (Samourai) medium medium (Samourai) (Samourai) fasciation (atflowering present (Gotte present (Gotte absent (Calmar, stage) Jauned'or) Jaune d'or) Romance) intensity of fasciation medium (Amadeus)medium (flowering plant) (Amadeus) head formation open head closed head/closed head/ (Manfred, Monet) overlapping overlapping semi open head(Kelvin, Sunrise) (Kelvin, Sunrise) head: degree of Weak (Danilla,medium medium overlapping of upper Novita) (Augusta, (Augusta, part ofplant (varieties Fiorella) Fiorella) with closed head formation only)head diameter (market 12.58 cm 14.32 cm 12.75 cm trimmed with single capleaf) head shape spherical spherical spherical head shape in circular(Passe circular (Passe circular (Passe longitudinal section Partout,Verpia) Partout, Verpia) Partout, Verpia) head size (class) medium(Fiorella, medium medium Soraya) (Fiorella, (Fiorella, Soraya) Soraya)heads per carton 24 24 24 head weight 534.9 gms 532.66 gms 336.35 gmshead firmness/density medium (Blonde medium (Blonde medium (Blondemaraîchère) maraîchère) maraîchère) 6. Butt shape flat flat flat midribmoderately moderately moderately raised raised raised 7. Core diameterat base of 29 mm 28.32 mm 26.13 mm head ratio of head diameter/ 4.3 4.955 core diameter core height from base 37.06 mm 35.95 mm 30.53 mm of headto apex 8. Bolting first water date Apr. 14, 2009 Apr. 14, 2009 Apr. 14,2009 number of days from 83 78 72 first water date to seed stalkemergence (summer conditions) bolting class slow slow rapid time ofbeginning of late (Hilde II) late (Hilde II) early to medium boltingunder long day conditions height of mature seed 98 cm 105 cm 93 cm stalkspread of bolter plant 58 cm 42 cm 58 cm (at widest point) bolter leavesstraight straight straight margin dentate dentate dentate color mediumgreen medium green dark green bolter habit: terminal present presentpresent inflorescence bolter habit: lateral present present presentshoots bolter habit: basal side present absent present shoots axillarysprouting strong (Riva) absent or very strong (Riva) weak (Valmaine)time of harvest maturity medium (Newton) medium Early (Newton)(Attraction) *These are typical values. Values may vary due toenvironment. Other values that are substantially equivalent are alsowithin the scope of the invention.

Line RX17275496 has been self-pollinated and planted for a number ofgenerations to produce the homozygosity and phenotypic stability to makethis line useful in commercial seed production. No variant traits havebeen observed or are expected for this line.

Lettuce line RX17275496, being substantially homozygous, can bereproduced by planting seeds of the line, growing the resulting lettuceplant under self-pollinating or sib-pollinating conditions andharvesting the resulting seeds using techniques familiar to one of skillin the art.

C. Breeding Lettuce Line RX17275496

One aspect of the current invention concerns methods for crossing thelettuce line RX17275496 with itself or a second plant and the seeds andplants produced by such methods. These methods can be used forpropagation of line RX17275496, or can be used to produce hybrid lettuceseeds and the plants grown therefrom. Hybrid seeds are produced bycrossing line RX17275496 with second lettuce parent line.

The development of new varieties using one or more starting varieties iswell known in the art. In accordance with the invention, novel varietiesmay be created by crossing line RX17275496 followed by multiplegenerations of breeding according to such well known methods. Newvarieties may be created by crossing with any second plant. In selectingsuch a second plant to cross for the purpose of developing novel lines,it may be desired to choose those plants which either themselves exhibitone or more selected desirable characteristics or which exhibit thedesired characteristic(s) when in hybrid combination. Once initialcrosses have been made, inbreeding and selection take place to producenew varieties. For development of a uniform line, often five or moregenerations of selfing and selection are involved.

Uniform lines of new varieties may also be developed by way ofdouble-haploids. This technique allows the creation of true breedinglines without the need for multiple generations of selfing andselection. In this manner true breeding lines can be produced in aslittle as one generation. Haploid embryos may be produced frommicrospores, pollen, anther cultures, or ovary cultures. The haploidembryos may then be doubled autonomously, or by chemical treatments(e.g. colchicine treatment). Alternatively, haploid embryos may be growninto haploid plants and treated to induce chromosome doubling. In eithercase, fertile homozygous plants are obtained. In accordance with theinvention, any of such techniques may be used in connection with lineRX17275496 and progeny thereof to achieve a homozygous line.

New varieties may be created, for example, by crossing line RX17275496with any second plant and selection of progeny in various generationsand/or by doubled haploid technology. In choosing a second plant tocross for the purpose of developing novel lines, it may be desired tochoose those plants which either themselves exhibit one or more selecteddesirable characteristics or which exhibit the desired characteristic(s)in progeny. After one or more lines are crossed, true-breeding lines maybe developed.

Backcrossing can also be used to improve an inbred plant. Backcrossingtransfers a specific desirable trait from one inbred or non-inbredsource to an inbred that lacks that trait. This can be accomplished, forexample, by first crossing a superior inbred (A) (recurrent parent) to adonor inbred (non-recurrent parent), which carries the appropriate locusor loci for the trait in question. The progeny of this cross are thenmated back to the superior recurrent parent (A) followed by selection inthe resultant progeny for the desired trait to be transferred from thenon-recurrent parent. After five or more backcross generations withselection for the desired trait, the progeny are heterozygous for locicontrolling the characteristic being transferred, but are like thesuperior parent for most or almost all other loci. The last backcrossgeneration would be selfed to give pure breeding progeny for the traitbeing transferred.

The line of the present invention is particularly well suited for thedevelopment of new lines based on the elite nature of the geneticbackground of the line. In selecting a second plant to cross withRX17275496 for the purpose of developing novel lettuce lines, it willtypically be preferred to choose those plants which either themselvesexhibit one or more selected desirable characteristics or which exhibitthe desired characteristic(s) when in hybrid combination.

D. Performance Characteristics

As described above, line RX17275496 exhibits desirable agronomic traits,including a Butterhead lettuce adapted to open-field growth; a mid-darkleaf color; a thick and smooth leaf; a fine and flat bottom; goodbolting resistance when grown in the field; white seed; resistance toraces 1-26 of Bremia lectucae (downy mildew), resistance to strain 0 ofNasonovia ribisnigri (Nr:0), and resistance to strain Ls-1 of lettucemosaic virus (LMV); and ease in harvesting and processing. These andother performance characteristics of the line were the subject of anobjective analysis of the performance traits of the line relative toother lines. The results of the analysis are presented below.

TABLE 2 Performance Characteristics For Line RX17275496 NAME OFPHENOTYPE OF PHENOTYPE COMPARISON CHARAC- COMPARISON OF VARIETY TERISTICVARIETY RX17275496 Lucan Head shape globe more flat and semi-openDiameter of medium medium-small the stem Touareg Head shape semi-closedsemi-open Volume medium medium/medium- large Leaf color medium dark;medium; and luster not shiny more shiny

E. Further Embodiments of the Invention

In specific embodiments, the invention provides plants modified toinclude at least a first desired heritable trait. Such plants may, inone embodiment, be developed by a plant breeding technique calledbackcrossing, wherein essentially all of the desired morphological andphysiological characteristics of a variety are recovered in addition toa genetic locus transferred into the plant via the backcrossingtechnique. The term single locus converted plant as used herein refersto those lettuce plants which are developed by a plant breedingtechnique called backcrossing, wherein essentially all of the desiredmorphological and physiological characteristics of a variety arerecovered in addition to the single locus transferred into the varietyvia the backcrossing technique.

Backcrossing methods can be used with the present invention to improveor introduce a characteristic into the present variety. The parentallettuce plant which contributes the locus for the desired characteristicis termed the nonrecurrent or donor parent. This terminology refers tothe fact that the nonrecurrent parent is used one time in the backcrossprotocol and therefore does not recur. The parental lettuce plant towhich the locus or loci from the nonrecurrent parent are transferred isknown as the recurrent parent as it is used for several rounds in thebackcrossing protocol.

In a typical backcross protocol, the original variety of interest(recurrent parent) is crossed to a second variety (nonrecurrent parent)that carries the single locus of interest to be transferred. Theresulting progeny from this cross are then crossed again to therecurrent parent and the process is repeated until a lettuce plant isobtained wherein essentially all of the desired morphological andphysiological characteristics of the recurrent parent are recovered inthe converted plant, in addition to the single transferred locus fromthe nonrecurrent parent.

The selection of a suitable recurrent parent is an important step for asuccessful backcrossing procedure. The goal of a backcross protocol isto alter or substitute a single trait or characteristic in the originalvariety. To accomplish this, a single locus of the recurrent variety ismodified or substituted with the desired locus from the nonrecurrentparent, while retaining essentially all of the rest of the desiredgenetic, and therefore the desired physiological and morphologicalconstitution of the original variety. The choice of the particularnonrecurrent parent will depend on the purpose of the backcross; one ofthe major purposes is to add some commercially desirable trait to theplant. The exact backcrossing protocol will depend on the characteristicor trait being altered to determine an appropriate testing protocol.Although backcrossing methods are simplified when the characteristicbeing transferred is a dominant allele, a recessive allele may also betransferred. In this instance it may be necessary to introduce a test ofthe progeny to determine if the desired characteristic has beensuccessfully transferred.

In one embodiment, progeny lettuce plants of a backcross in whichRX17275496 is the recurrent parent comprise (i) the desired trait fromthe non-recurrent parent and (ii) all of the physiological andmorphological characteristics of lettuce line RX17275496 as determinedat the 5% significance level when grown in the same environmentalconditions.

Lettuce varieties can also be developed from more than two parents. Thetechnique, known as modified backcrossing, uses different recurrentparents during the backcrossing. Modified backcrossing may be used toreplace the original recurrent parent with a variety having certain moredesirable characteristics or multiple parents may be used to obtaindifferent desirable characteristics from each.

Many single locus traits have been identified that are not regularlyselected for in the development of a new inbred but that can be improvedby backcrossing techniques. Single locus traits may or may not betransgenic; examples of these traits include, but are not limited to,male sterility, herbicide resistance, resistance to bacterial, fungal,or viral disease, insect resistance, restoration of male fertility,modified fatty acid or carbohydrate metabolism, and enhanced nutritionalquality. These comprise genes generally inherited through the nucleus.

Direct selection may be applied where the single locus acts as adominant trait. An example of a dominant trait is the downy mildewresistance trait. For this selection process, the progeny of the initialcross are sprayed with downy mildew spores prior to the backcrossing.The spraying eliminates any plants which do not have the desired downymildew resistance characteristic, and only those plants which have thedowny mildew resistance gene are used in the subsequent backcross. Thisprocess is then repeated for all additional backcross generations.

Selection of lettuce plants for breeding is not necessarily dependent onthe phenotype of a plant and instead can be based on geneticinvestigations. For example, one can utilize a suitable genetic markerwhich is closely genetically linked to a trait of interest. One of thesemarkers can be used to identify the presence or absence of a trait inthe offspring of a particular cross, and can be used in selection ofprogeny for continued breeding. This technique is commonly referred toas marker assisted selection. Any other type of genetic marker or otherassay which is able to identify the relative presence or absence of atrait of interest in a plant can also be useful for breeding purposes.Procedures for marker assisted selection applicable to the breeding oflettuce are well known in the art. Such methods will be of particularutility in the case of recessive traits and variable phenotypes, orwhere conventional assays may be more expensive, time consuming orotherwise disadvantageous. Types of genetic markers which could be usedin accordance with the invention include, but are not necessarilylimited to, Simple Sequence Length Polymorphisms (SSLPs) (Williams etal., 1990), Randomly Amplified Polymorphic DNAs (RAPDs), DNAAmplification Fingerprinting (DAF), Sequence Characterized AmplifiedRegions (SCARs), Arbitrary Primed Polymerase Chain Reaction (AP-PCR),Amplified Fragment Length Polymorphisms (AFLPs) (EP 534 858,specifically incorporated herein by reference in its entirety), andSingle Nucleotide Polymorphisms (SNPs) (Wang et al., 1998).

F. Plants Derived From Lettuce Line RX17275496 by Genetic Engineering

Many useful traits that can be introduced by backcrossing, as well asdirectly into a plant, are those which are introduced by genetictransformation techniques. Genetic transformation may therefore be usedto insert a selected transgene into the lettuce line of the invention ormay, alternatively, be used for the preparation of transgenes which canbe introduced by backcrossing. Methods for the transformation of plants,including lettuce, are well known to those of skill in the art.

Vectors used for the transformation of lettuce cells are not limited solong as the vector can express an inserted DNA in the cells. Forexample, vectors comprising promoters for constitutive gene expressionin lettuce cells (e.g., cauliflower mosaic virus 35S promoter) andpromoters inducible by exogenous stimuli can be used. Examples ofsuitable vectors include pBI binary vector. The “lettuce cell” intowhich the vector is to be introduced includes various forms of lettucecells, such as cultured cell suspensions, protoplasts, leaf sections,and callus.

A vector can be introduced into lettuce cells by known methods, such asthe polyethylene glycol method, polycation method, electroporation,Agrobacterium-mediated transfer, particle bombardment and direct DNAuptake by protoplasts. See, e.g., Pang et al. (1996).

To effect transformation by electroporation, one may employ eitherfriable tissues, such as a suspension culture of cells or embryogeniccallus or alternatively one may transform immature embryos or otherorganized tissue directly. In this technique, one would partiallydegrade the cell walls of the chosen cells by exposing them topectin-degrading enzymes (pectolyases) or mechanically wound tissues ina controlled manner. An example of electroporation of lettuceprotoplasts is presented in Chupeau et al. (1989).

A particularly efficient method for delivering transforming DNA segmentsto plant cells is microprojectile bombardment. In this method, particlesare coated with nucleic acids and delivered into cells by a propellingforce. Exemplary particles include those comprised of tungsten,platinum, and preferably, gold. For the bombardment, cells in suspensionare concentrated on filters or solid culture medium. Alternatively,immature embryos or other target cells may be arranged on solid culturemedium. The cells to be bombarded are positioned at an appropriatedistance below the macroprojectile stopping plate.

An illustrative embodiment of a method for delivering DNA into plantcells by acceleration is the Biolistics Particle Delivery System, whichcan be used to propel particles coated with DNA or cells through ascreen, such as a stainless steel or Nytex screen, onto a surfacecovered with target lettuce cells. The screen disperses the particles sothat they are not delivered to the recipient cells in large aggregates.It is believed that a screen intervening between the projectileapparatus and the cells to be bombarded reduces the size of projectilesaggregate and may contribute to a higher frequency of transformation byreducing the damage inflicted on the recipient cells by projectiles thatare too large.

Microprojectile bombardment techniques are widely applicable, and may beused to transform virtually any plant species. Examples involvingmicroprojectile bombardment transformation with lettuce can be found in,for example, Elliott et al. (2004) and Molinier et al. (2002).

Agrobacterium-mediated transfer is another widely applicable system forintroducing gene loci into plant cells. An advantage of the technique isthat DNA can be introduced into whole plant tissues, thereby bypassingthe need for regeneration of an intact plant from a protoplast. ModernAgrobacterium transformation vectors are capable of replication in E.coli as well as Agrobacterium, allowing for convenient manipulations(Klee et al., 1985). Moreover, recent technological advances in vectorsfor Agrobacterium-mediated gene transfer have improved the arrangementof genes and restriction sites in the vectors to facilitate theconstruction of vectors capable of expressing various polypeptide codinggenes. The vectors described have convenient multi-linker regionsflanked by a promoter and a polyadenylation site for direct expressionof inserted polypeptide coding genes. Additionally, Agrobacteriumcontaining both armed and disarmed Ti genes can be used fortransformation.

In those plant strains where Agrobacterium-mediated transformation isefficient, it is the method of choice because of the facile and definednature of the gene locus transfer. The use of Agrobacterium-mediatedplant integrating vectors to introduce DNA into plant cells is wellknown in the art (Fraley et al., 1985; U.S. Pat. No. 5,563,055). Forexample, U.S. Pat. No. 5,349,124 describes a method of transforminglettuce plant cells using Agrobacterium-mediated transformation. Byinserting a chimeric gene having a DNA coding sequence encoding for thefull-length B.t. toxin protein that expresses a protein toxic towardLepidopteran larvae, this methodology resulted in lettuce havingresistance to such insects.

Transformation of plant protoplasts also can be achieved using methodsbased on calcium phosphate precipitation, polyethylene glycol treatment,electroporation, and combinations of these treatments (see, e.g.,Potrykus et al., 1985; Omirulleh et al., 1993; Fromm et al., 1986;Uchimiya et al., 1986; Marcotte et al., 1988). Transformation of plantsand expression of foreign genetic elements is exemplified in Choi et al.(1994) and Ellul et al. (2003).

A number of promoters have utility for plant gene expression for anygene of interest including but not limited to selectable markers,scoreable markers, genes for pest tolerance, disease resistance,nutritional enhancements and any other gene of agronomic interest.Examples of constitutive promoters useful for lettuce plant geneexpression include, but are not limited to, the cauliflower mosaic virus(CaMV) P-35S promoter, which confers constitutive, high-level expressionin most plant tissues (see, e.g., Odel et al., 1985), including monocots(see, e.g., Dekeyser et al., 1990; Terada and Shimamoto, 1990); atandemly duplicated version of the CaMV 35S promoter, the enhanced 35Spromoter (P-e35S) the nopaline synthase promoter (An et al., 1988), theoctopine synthase promoter (Fromm et al., 1989); and the figwort mosaicvirus (P-FMV) promoter as described in U.S. Pat. No. 5,378,619 and anenhanced version of the FMV promoter (P-eFMV) where the promotersequence of P-FMV is duplicated in tandem, the cauliflower mosaic virus19S promoter, a sugarcane bacilliform virus promoter, a commelina yellowmottle virus promoter, and other plant DNA virus promoters known toexpress in plant cells.

A variety of plant gene promoters that are regulated in response toenvironmental, hormonal, chemical, and/or developmental signals can beused for expression of an operably linked gene in plant cells, includingpromoters regulated by (1) heat (Callis et al., 1988), (2) light (e.g.,pea rbcS-3A promoter, Kuhlemeier et al., 1989; maize rbcS promoter,Schaffner and Sheen, 1991; or chlorophyll a/b-binding protein promoter,Simpson et al., 1985), (3) hormones, such as abscisic acid (Marcotte etal., 1989), (4) wounding (e.g., wunl, Siebertz et al., 1989); or (5)chemicals such as methyl jasmonate, salicylic acid, or Safener. It mayalso be advantageous to employ organ-specific promoters (e.g., Roshal etal., 1987; Schernthaner et al., 1988; Bustos et al., 1989).

Exemplary nucleic acids which may be introduced to the lettuce lines ofthis invention include, for example, DNA sequences or genes from anotherspecies, or even genes or sequences which originate with or are presentin the same species, but are incorporated into recipient cells bygenetic engineering methods rather than classical reproduction orbreeding techniques. However, the term “exogenous” is also intended torefer to genes that are not normally present in the cell beingtransformed, or perhaps simply not present in the form, structure, etc.,as found in the transforming DNA segment or gene, or genes which arenormally present and that one desires to express in a manner thatdiffers from the natural expression pattern, e.g., to over-express.Thus, the term “exogenous” gene or DNA is intended to refer to any geneor DNA segment that is introduced into a recipient cell, regardless ofwhether a similar gene may already be present in such a cell. The typeof DNA included in the exogenous DNA can include DNA which is alreadypresent in the plant cell, DNA from another plant, DNA from a differentorganism, or a DNA generated externally, such as a DNA sequencecontaining an antisense message of a gene, or a DNA sequence encoding asynthetic or modified version of a gene.

Many hundreds if not thousands of different genes are known and couldpotentially be introduced into a lettuce plant according to theinvention. Non-limiting examples of particular genes and correspondingphenotypes one may choose to introduce into a lettuce plant include oneor more genes for insect tolerance, such as a Bacillus thuringiensis(B.t.) gene, pest tolerance such as genes for fungal disease control,herbicide tolerance such as genes conferring glyphosate tolerance, andgenes for quality improvements such as yield, nutritional enhancements,environmental or stress tolerances, or any desirable changes in plantphysiology, growth, development, morphology or plant product(s). Forexample, structural genes would include any gene that confers insecttolerance including but not limited to a Bacillus insect control proteingene as described in WO 99/31248, herein incorporated by reference inits entirety, U.S. Pat. No. 5,689,052, herein incorporated by referencein its entirety, U.S. Pat. Nos. 5,500,365 and 5,880,275, hereinincorporated by reference it their entirety. In another embodiment, thestructural gene can confer tolerance to the herbicide glyphosate asconferred by genes including, but not limited to Agrobacterium strainCP4 glyphosate resistant EPSPS gene (aroA:CP4) as described in U.S. Pat.No. 5,633,435, herein incorporated by reference in its entirety, orglyphosate oxidoreductase gene (GOX) as described in U.S. Pat. No.5,463,175, herein incorporated by reference in its entirety.

Alternatively, the DNA coding sequences can affect these phenotypes byencoding a non-translatable RNA molecule that causes the targetedinhibition of expression of an endogenous gene, for example viaantisense- or cosuppression-mediated mechanisms (see, for example, Birdet al., 1991). The RNA could also be a catalytic RNA molecule (i.e., aribozyme) engineered to cleave a desired endogenous mRNA product (seefor example, Gibson and Shillito, 1997). Thus, any gene which produces aprotein or mRNA which expresses a phenotype or morphology change ofinterest is useful for the practice of the present invention.

G. Definitions

In the description and tables herein, a number of terms are used. Inorder to provide a clear and consistent understanding of thespecification and claims, the following definitions are provided:

Allele: Any of one or more alternative forms of a gene locus, all ofwhich alleles relate to one trait or characteristic. In a diploid cellor organism, the two alleles of a given gene occupy corresponding locion a pair of homologous chromosomes.

Backcrossing: A process in which a breeder repeatedly crosses hybridprogeny, for example a first generation hybrid (F₁), back to one of theparents of the hybrid progeny. Backcrossing can be used to introduce oneor more single locus conversions from one genetic background intoanother.

Crossing: The mating of two parent plants.

Cross-pollination: Fertilization by the union of two gametes fromdifferent plants.

Diploid: A cell or organism having two sets of chromosomes.

Emasculate: The removal of plant male sex organs or the inactivation ofthe organs with a cytoplasmic or nuclear genetic factor or a chemicalagent conferring male sterility.

Enzymes: Molecules which can act as catalysts in biological reactions.

F₁ Hybrid: The first generation progeny of the cross of two nonisogenicplants.

Genotype: The genetic constitution of a cell or organism.

Haploid: A cell or organism having one set of the two sets ofchromosomes in a diploid.

Linkage: A phenomenon wherein alleles on the same chromosome tend tosegregate together more often than expected by chance if theirtransmission was independent.

Marker: A readily detectable phenotype, preferably inherited incodominant fashion (both alleles at a locus in a diploid heterozygoteare readily detectable), with no environmental variance component, i.e.,heritability of 1.

Phenotype: The detectable characteristics of a cell or organism, whichcharacteristics are the manifestation of gene expression.

Quantitative Trait Loci (QTL): Quantitative trait loci (QTL) refer togenetic loci that control to some degree numerically representabletraits that are usually continuously distributed.

Regeneration: The development of a plant from tissue culture.

Royal Horticultural Society (RHS) color chart value: The RHS color chartis a standardized reference which allows accurate identification of anycolor. A color's designation on the chart describes its hue, brightnessand saturation. A color is precisely named by the RHS color chart byidentifying the group name, sheet number and letter, e.g., Yellow-OrangeGroup 19A or Red Group 41B.

Self-pollination: The transfer of pollen from the anther to the stigmaof the same plant.

Single Locus Converted (Conversion) Plant: Plants which are developed bya plant breeding technique called backcrossing, wherein essentially allof the desired morphological and physiological characteristics of alettuce variety are recovered in addition to the characteristics of thesingle locus transferred into the variety via the backcrossing techniqueand/or by genetic transformation.

Substantially Equivalent: A characteristic that, when compared, does notshow a statistically significant difference (e.g., p=0.05) from themean.

Tetraploid: A cell or organism having four sets of chromosomes.

Tissue Culture: A composition comprising isolated cells of the same or adifferent type or a collection of such cells organized into parts of aplant.

Transgene: A genetic locus comprising a sequence which has beenintroduced into the genome of a lettuce plant by transformation.

Triploid: A cell or organism having three sets of chromosomes.

H. Deposit Information

A deposit of lettuce line RX17275496, disclosed above and recited in theclaims, has been made with the American Type Culture Collection (ATCC),10801 University Blvd., Manassas, Va. 20110-2209. The date of depositwas Mar. 29, 2010. Upon issuance of a patent, all restrictions upon thedeposit will be removed, and the deposit is intended to meet all of therequirements of 37 C.F.R. §1.801-1.809. The accession number for thosedeposited seeds of lettuce line RX17275496 is ATCC Accession No.PTA-10734. The deposit will be maintained in the depository for a periodof 30 years, or 5 years after the last request, or for the effectivelife of the patent, whichever is longer, and will be replaced ifnecessary during that period.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity andunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the invention, as limited only bythe scope of the appended claims.

All references cited herein are hereby expressly incorporated herein byreference.

REFERENCES

The following references, to the extent that they provide exemplaryprocedural or other details supplementary to those set forth herein, arespecifically incorporated herein by reference:

-   U.S. Pat. No. 5,349,124-   U.S. Pat. No. 5,378,619-   U.S. Pat. No. 5,463,175-   U.S. Pat. No. 5,500,365-   U.S. Pat. No. 5,563,055-   U.S. Pat. No. 5,633,435-   U.S. Pat. No. 5,689,052-   U.S. Pat. No. 5,880,275-   An et al., Plant Physiol., 88:547, 1988.-   Bird et al., Biotech. Gen. Engin. Rev., 9:207, 1991.-   Bustos et al., Plant Cell, 1:839, 1989.-   Callis et al., Plant Physiol., 88:965, 1988.-   Choi et al., Plant Cell Rep., 13: 344-348, 1994.-   Chupeau et al., Bio/Tech., 7:503-508, 1989.-   Dekeyser et al., Plant Cell, 2:591, 1990.-   Elliott et al., Plant Cell Rep., 18:707-714, 2004.-   Ellul et al., Theor. Appl. Genet., 107:462-469, 2003.-   EP 534 858-   Fraley et al., Bio/Technology, 3:629-635, 1985.-   Fromm et al., Nature, 312:791-793, 1986.-   Fromm et al., Plant Cell, 1:977, 1989.-   Gibson and Shillito, Mol. Biotech., 7:125, 1997-   Klee et al., Bio-Technology, 3(7):637-642, 1985.-   Kuhlemeier et al., Plant Cell, 1:471, 1989.-   Marcotte et al., Nature, 335:454, 1988.-   Marcotte et al., Plant Cell, 1:969, 1989.-   Molinier et al., Plant Cell Rep., 21:251-256, 2002.-   Odel et al., Nature, 313:810, 1985.-   Omirulleh et al., Plant Mol. Biol., 21(3):415-428, 1993.-   Pang et al., The Plant J., 9, 899-909, 1996.-   Potrykus et al., Mol. Gen. Genet., 199:183-188, 1985.-   Roshal et al., EMBO J., 6:1155, 1987.-   Ryder, In: Breeding Vegetable Crops, AVI Pub., Westport, Conn.,    433-474, 1986.-   Schaffner and Sheen, Plant Cell, 3:997, 1991.-   Schernthaner et al., EMBO J., 7:1249, 1988.-   Siebertz et al., Plant Cell, 1:961, 1989.-   Simpson et al., EMBO J., 4:2723, 1985.-   Terada and Shimamoto, Mol. Gen. Genet., 220:389, 1990.-   Uchimiya et al., Mol. Gen. Genet., 204:204, 1986.-   Wang et al., Science, 280:1077-1082, 1998.-   Williams et al., Nucleic Acids Res., 1 8:6531-6535, 1990.-   WO 99/31248

What is claimed is:
 1. A seed of lettuce line RX17275496, a sample ofseed of said line having been deposited under ATCC Accession NumberPTA-10734.
 2. A plant grown from the seed of claim
 1. 3. A plant part ofthe plant of claim
 2. 4. The plant part of claim 3, wherein said part isselected from the group consisting of a, pollen, an ovule and a cell. 5.A lettuce plant, or a part thereof, having all the physiological andmorphological characteristics of the lettuce plant of claim
 2. 6. Atissue culture of regenerable cells of lettuce line RX17275496, a sampleof seed of said line having been deposited under ATCC Accession NumberPTA-10734.
 7. The tissue culture according to claim 6, comprising cellsor protoplasts from a plant part selected from the group consisting ofembryos, meristems, cotyledons, pollen, leaves, anthers, roots, roottips, pistil, flower, seed and stalks.
 8. A lettuce plant regeneratedfrom the tissue culture of claim 6, wherein the regenerated plantexpresses all of the physiological and morphological characteristics oflettuce line RX17275496, a sample of seed of said line having beendeposited under ATCC Accession Number PTA-10734.
 9. A method ofproducing lettuce seed, comprising crossing the plant of claim 2 with asecond lettuce plant.
 10. The method of claim 9, wherein the plant oflettuce line RX17275496 is the female parent.
 11. An F1 hybrid seedproduced by the method of claim
 9. 12. An F1 hybrid plant produced bygrowing the seed of claim
 11. 13. A method for producing a seed of aline RX17275496-derived lettuce plant comprising the steps of: (a)crossing a lettuce plant of line RX17275496, a sample of seed of saidline having been deposited under ATCC Accession Number PTA-10734, with asecond lettuce plant; and (b) allowing seed of a RX17275496-derivedlettuce plant to form.
 14. The method of claim 13, further comprisingthe steps of: (c) crossing a plant grown from said RX17275496-derivedlettuce seed with itself or a second lettuce plant to yield additionalRX17275496-derived lettuce seed; (d) growing said additionalRX17275496-derived lettuce seed of step (c) to yield additionalRX17275496-derived lettuce plants; and (e) repeating the crossing andgrowing steps of (c) and (d) to generate further RX17275496-derivedlettuce plants.
 15. A method of vegetatively propagating a plant oflettuce line RX17275496 comprising the steps of: (a) collecting tissuecapable of being propagated from a plant of lettuce line RX17275496, asample of seed of said line having been deposited under ATCC AccessionNumber PTA-10734; (b) cultivating said tissue to obtain proliferatedshoots; and (c) rooting said proliferated shoots to obtain rootedplantlets.
 16. The method of claim 15, further comprising growing plantsfrom said rooted plantlets.
 17. A method of introducing a desired traitinto lettuce line RX17275496 comprising: (a) crossing a plant of lineRX17275496, a sample of seed of said line having been deposited underATCC Accession Number PTA-10734, with a second lettuce plant thatcomprises a desired trait to produce F1 progeny; (b) selecting an F1progeny that comprises the desired trait; (c) crossing the selected F1progeny with a plant of line RX17275496, to produce backcross progeny;(d) selecting backcross progeny comprising the desired trait and thephysiological and morphological characteristic of lettuce lineRX17275496; and (e) repeating steps (c) and (d) three or more times insuccession to produce selected fourth or higher backcross progeny thatcomprise the desired trait and all of the physiological andmorphological characteristics of lettuce line RX17275496 when grown inthe same environmental conditions.
 18. A lettuce plant produced by themethod of claim
 17. 19. A method of producing a plant of lettuce lineRX17275496, a sample of seed of said line having been deposited underATCC Accession Number PTA-10734, comprising an added desired trait, themethod comprising introducing a transgene conferring the desired traitinto a plant of lettuce line RX17275496.
 20. A method of producinglettuce comprising: (a) obtaining the plant of claim 2, and (b)collecting lettuce from the plant.